Refreshes the OS environment.
EnvUpdate (  )
| Success: | none. | 
| Failure: | sets the @error flag to 1. | 
Similar effect as logging off and then on again. For example, changes to the %path% environment might not take effect until you call EnvUpdate() (or you logoff/reboot).
#include <MsgBoxConstants.au3>
Example()
Func Example()
    ; Retrieve the system environment variable called %PATH%.
    Local $sEnvVar = EnvGet("PATH")
    ; Assign the system environment variable called %PATH% with its current value as well as the script directory.
    ; When you assign an environment variable you do so minus the percentage signs (%).
    EnvSet("PATH", $sEnvVar & ";" & @ScriptDir)
    ; Refresh the OS environment for changes to take affect.
    EnvUpdate()
    ; Retrieve the system environment variable that was just assigned a value previously.
    $sEnvVar = EnvGet("PATH")
    ; Display the value of the environment variable $PATH%.
    MsgBox($MB_SYSTEMMODAL, "", "The environment variable %PATH% has the value of: " & $sEnvVar)
EndFunc   ;==>Example